Abstract

With water recycling schemes (such as greywater treatment and reuse) set to increase in water stressed areas, additional research is required to elucidate the fate of xenobiotics in greywater during treatment and to identify the possible implications of more widespread greywater recycling for urban wastewater loads and dynamics. In this paper, scenario analyses are used to highlight the potential fate of a selection of xenobiotics in decentralised greywater treatment systems, and to investigate the possible implications of greywater recycling for the urban water cycle. Scenario analyses based on Danish water use statistics and priority substance monitoring at a greywater treatment plant in Copenhagen, Denmark, showed that greywater recycling can potentially save significant volumes of potable water. However, it is also clear that careful consideration must be paid to greywater treatment system design and maintenance to ensure that potential risks associated with persistent pollutant buildup are avoided. On the basis of current designs, the results also indicate that with respect to persistent/non-biodegradable micropollutants the major benefits to be gained from greywater recycling are in relation to potable water savings rather than pollutant source control.